So they set up a very powerful Teleportation Array on the inevitable path through the thunder sea. This kind of array wouldn't be noticed by those at the Meridian Opening stage, but it would be discovered by individuals at the God Refining stage.
There were God Refining judges patrolling that area, and powerful martial artists were all nearby. A moment's inattention could easily lead to the judges detecting something amiss and then ending the contest, at which point their plan would fall through completely.
Thus, the Ghost Mustache of Remnant Visage didn't directly target any particular student team but instead sought to lure more students to the withered forest before making a move.